This invention relates to improvements in a behind-the-ear type hearing aid.
Conventional behind-the-ear type hearing aids have comprised a main body and a hook extending from the main body and arranged to engage the upper end of the earlobe of the user to hang the main body on the ear thereof. Those hearing aids have been divided into the front and bottom microphone types. In the front microphone type, a microphone has been disposed on an upper or a lower side of the front end of the main body and in the bottom microphone type, a microphone has been disposed on a bottom, a lateral side or the rear end of the main body. A self-contained amplifier has then been disposed within the main body so as to be connected across the microphone and an associated receiver which, in turn, communicates with the external auditory meatus of the user through a sound passageway extending through the main body and the hook.
The microphone has been generally used with normal conversation but may be also used to receive voices from a receiver of a telephone handset by placing the same against the receiver. At that time, the microphone of the bottom microphone type has occupied a position which is convenient to receive voices from the telephone receiver but it has been objectionable when used with normal conversations because wind noise may occur about the microphone. On the other hand, the microphone of the front microphone type has been disadvantageous in that, as the same is disposed on the upper portion of the main body, the telephone receiver must be located on the upper portion of the ear of the user which is inevitably attended with the telephone transmitter positioned so as to be spaced from the user's mouth, resulting in the front microphone type being hard to be used. In addition, the front microphone type has encountered the problem that voice from the telephone receiver partly leaks through an associated ear plug inserted into the external auditory meatus of the user so as to reach the front surface of the telephone receiver with the result that howling is apt to occur.
As a result, it has been undesirable to selectively use the single microphone on behind-the-ear type hearing aids with both normal and telephone conversation.
There have been already known behind-the-air hearing aids comprising a microphone for use with normal conversations and a telephone pickup coil for picking up a magnetic leakage flux from an associated telephone set for purposes of telephone conversation. However, telephone sets have been further improved to decrease the magnetic leakage flux therefrom to an extent that it is inevitably difficult to utilize telephone pickup coils for telephone conversations.
Accordingly, it is an object of the present invention to provide a new and improved behind-the-ear type hearing aid capable of hearing voices from a telephone set which are substantially free from a magnetic leakage flux therefrom.